Aerodynamic loads experienced by aircraft structures, such as an aircraft wing, include, e.g., bending loads. Tough and lightweight composite materials are increasingly used in the construction of aircraft wings because they are capable of supporting the loads encountered during flight while enabling a decrease in weight of the aircraft. A common type of composite material used in aircraft construction is carbon fiber composite.
Generally, a wingbox structure of the aircraft wing includes a stiffened upper panel (or skin), a stiffened lower panel (or skin), opposed spars that connect to leading and trailing edges of the panels, and internal ribs that provide shape and support to the wingbox structure and connect the panels. It is desirable to decrease the thickness of the wing, particularly an outboard portion of the wing, as much as possible to improve the aerodynamic efficiency of the aircraft (e.g., a thicker wing encounters more drag). However, decreasing wing thickness continues to be a structural challenge because the height of the stiffeners limits how thin the wing can be constructed in view of the fact that the use of stiffeners having a reduced height to decrease wing thickness is limited. Low-profile stiffeners may be used to stiffen the lower panel since the lower panel is primarily in tension during flight. However, low profile-stiffeners are not suitable for the upper panel. High-profile stiffeners (e.g., stiffeners having a taller cross-sectional profile), such as I-shaped or T-shaped stiffeners, are needed to stiffen at least the majority of the upper panel since the upper panel is primary in compression during flight.